<i>CmPPR4</i> gene controls drought resilience in melon ecotypes

Global climate change has rendered drought stress an increasing threat to sustainable crop production. Melon (Cucumis melo) crop is widely cultivated worldwide, and has been classified into two subspecies C. melo ssp. melo and C. melo ssp. agrestis with greater drought tolerance variation. However, the genetic basis for the difference in drought resilience between two subspecies ecotypes remains unclear. In this study, we constructed an F₈ recombinant inbred lines (RILs) population generated by crossing drought-tolerant C. melo ssp. melo with drought-sensitive C. melo ssp. agrestis and identified a CmPPR4 gene that encoded a pentatricopeptide repeat (PPR) protein highly associated with drought tolerance. A single nucleotide polymorphism (SNP) variation in CmPPR4 resulted in a nonsynonymous mutation, leading to reduced drought resilience in C. melo ssp. agrestis. The geographical distribution of CmPPR4 genotypes among 297 melon accessions closely parallels global annual precipitation patterns. Furthermore, the diminished drought tolerant capacity in RNA silencing seedlings and enhanced drought tolerance in overexpression lines further confirmed CmPPR4 as a crucial regulator of drought tolerance in melon. Collectively, our findings provide new insights into the crucial role of CmPPR4 in regulating drought tolerance of melon ecotypes, promoting molecular breeding of water-saving and drought-resilient melon cultivars.